September 30, 2011

seasonal plant maintenance

If you saw our Show two weeks ago, you may have seen my glowing example of a cold-damaged Episcia. I had nonchalantly left it outside on Thursday night when our temperatures dipped below 50F. The next day, it still looked somewhat presentable when I entered it into the Show, but by Sunday afternoon it was so distressed I pronounced it dead. (Episcias sulk at anything below 70F, so cold and wet at under 50F is guaranteed disaster - I know this, and knew this, and yet....)

Although recently temperatures have been mild and humidity high, autumn weather should be arriving soon - just in time for October. Perhaps this is a good time to fish out something I wrote up 9 months ago....

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I am actually writing this in January, when I am already seeing the “fruits” of my lackluster winter care. I think I was unusually inconsiderate (to the houseplants) this winter, but then again, I might be conveniently forgetting that I do the same thing every year.

is it possible
Don't let this be you.  Photo from January 2011: a Petrocosmea that wasn't given enough humidity through a heated winter.

Anyway, by the time you read this, it will be autumn and winter will be on its way again. Home growing environments tend to turn unfriendly to many gesneriads - dry air, cold drafts, cold windowsills..... What do you do to help your gesneriad collection emerge in good shape in the spring?

Some tips (mostly for home growers in winter, not greenhouse growers):

· Pest control.

Check for pests early, especially if you need to do any treatment outdoors.

· Check for cold spots.

Windows, windowsills, doorways, walls.... Look for cold spots and check if the plants in those locations can take the cold. Feel your windowsills - depending on the construction material, they may literally be freezing cold.

· Check south-facing windows

Check plants in south-facing windows to make sure they aren’t getting too much light during this time of year.

· Take cuttings.

Put down some cuttings of your favorite cold-sensitive plants like Episcia and keep them in a warm humid spot. Backup is always good.

· Rhizomatous plants.

Some rhizomatous plants like Kohleria may keep growing through the winter in a warm growing area. Others adhere to their internal clocks and will go dormant even if they are in a tropically warm environment. If the plants are dying back, rhizomes can be stored at room temperature or slightly cooler. Kohleria rhizomes can be kept slightly moist, whereas Achimenes rhizomes tend to rot easily and should be kept drier. Either way, it’s helpful to store them in a plastic bag so you can make sure they are not molding or drying up.

· Humidify.

Humidity-sensitive plants like Petrocosmea and Episcia may need extra help when the dry air arrives. You could use a humidity dome, humidifier, humidity trays or reservoirs (if it’s warm enough for the water to evaporate), clear color-less plastic containers, etc. If you are growing in sunlight, be careful with any enclosure as the sun can heat enclosed air to ungrowable temperatures. Grouping plants together, periodic showers, double-potting into a second pot filled loosely with long fiber sphagnum moss, are other tricks that might help.

· Watch your watering.

Plants’ water needs tend to go hand-in-hand with their growth rates. In other words, if they are growing less in the winter, they will need less water. But, there is a catch. If you have a warm, dry growing area (such as in a heated home), the pots may dry up much faster in winter than in summer - I have to INCREASE my watering through the winter for all non-dormant plants that are not in an enclosure.

· Trimming and pruning.

Some plants may benefit from some trimming or pruning. For example, some of my Sinningia continue growing weakly on the light shelves, whereas they would be dormant through the winter in a more natural environment. I trim them back sometime in the winter, especially in late winter if there are new shoots emerging.

Do you have more tips?  Send me an email - I'd love to hear them.